Many of us live
in a world of urban constellations, unable to see the stellar constellations
a moderately dark sky would provide. We should ask ourselves whether this is
the legacy we wish to leave our children. The dark sky is a natural resource
that should be protected. The ongoing loss of a dark night sky for much of the
world’s population is a growing, serious issue that impacts not only astronomical
research, but also human health, ecology and ecosystems, safety and security,
and energy conservation. Up to $10 billion dollars is wasted each year in the
United States by lighting up the underbellies of birds and clouds.1,2
According to the United Nations, 2008 will be the first year in which 3.3 billion
people, over half of the world's population, will live in cities.3
With the growth of large cities in Africa and Asia, the number of people living
in cities could climb to 5 billion by 2030. As cities grow, so does their impact
on the global environment.

In particular,
light pollution has a negative influence on a variety of animals and plants
in a variety of ways. It has been shown to disorient animals. Light pollution
affects mating, alters predator-prey behavior, confuses migration, and influences
animal physiology. Effects have been observed over a full range of taxonomic
groups, including birds, reptiles, mammals, amphibians, fishes, invertebrates,
and plants. Here in particular we will discuss the effects of nighttime artificial
lighting on sea turtles, birds, frogs, salamanders, insects, plants and fish.

Constant artificial
night lighting may disorient animals accustomed to navigating in the dark. The
most well-known example of this is the disorientation of sea turtles hatching
from nests on coastal beaches. Under normal circumstances, hatchlings move away
from low, dark silhouettes (e.g., of dune vegetation), allowing them to quickly
locate and crawl into the ocean. With beachfront lighting, the silhouettes that
would have cued movement are no longer visible, resulting in disorientation.4
Lighting also affects the egg-laying behavior of female sea turtles.5,6.

Birds can be disoriented
by artificial lights at night.7 A prime example
is juvenile seabirds as they leave their nests and fly out to sea. Lighted towers
and tall buildings can confuse migrating and local birds, leading to collisions
with other birds, structures or windows, or circling the lights until they die
of exhaustion. Artificial lighting has attracted birds to smokestacks, broadcast
towers,7 lighthouses,8
boats,9 greenhouses, oil platforms,10
and other structures at night. Estimates by the U.S. Fish and Wildlife Service
of the number of birds killed after being attracted to tall towers range from
4-5 million per year to an order of magnitude higher.11
The Fatal Light Awareness Program (FLAP)12 works
with building owners in Toronto, Canada and other cities to reduce mortality
of birds by turning out lights during migration periods.

Blacktailed
Goodwits

Some evidence suggests
that artificial lighting at night affects the choice of nesting sites for birds.
One example is black-tailed godwits in wet grassland habitats.13
Over 2 years, breeding densities of godwits were recorded. Lighted and unlighted
conditions near a roadway and near light poles were compared. When all other
habitat factors were taken into account, the density of nests was statistically
lower up to 300 meters away from the lighting at roadway and control sites.
Researchers also noted that birds nesting earlier in the year chose sites farther
away from the lights, while those nesting later filled in sites closer.

Changes in light
level may also disrupt orientation in nocturnal animals. Rapid increases in
light can blind animals, like frogs. The recovery time for frogs may be minutes
to hours.14 After getting used to a light, frogs
may be attracted to it as well.15 Artificial night
lighting may also affect reproductive behaviors. For example, female physalaemus
pustulosus frogs, are less selective about choosing a mate choice when light
levels are increased, presumably preferring to mate quickly and avoid an increased
chance of predators.16 Sky glow around sports
stadiums caused by artificial light at night can halt the mating activity of
nearby frogs. Like nocturnal frogs, salamanders are also affected by light pollution.
As nocturnal animals, they wake up when there is no light. Light pollution may
cause salamanders to come out from undercover later, giving them less time to
mate.

Moths, like many
groups of insects, are attracted to lights.17
Entomologists have documented that artificial light at night may interfere with
the ability of moths and other nocturnal insects to navigate.18
As a result, night blooming flowers that depend on moths for pollination may
be affected. This can lead to the decline of a plant species because they are
unable to reproduce and would change an area's long-term ecology. Other insects
attracted to lights include beetles, bugs, bush crickets, caddisflies, crane
flies, hoverflies, lacewings, midges, and wasps.19,20
Glowworms and fireflies are among species that communicate through light (bioluminescent
flashes). Artificial lighting can greatly reduce their visibility.

Studies suggest
that light pollution around lakes prevents zooplankton, such as Daphnia, from
eating surface algae, helping cause algal blooms that can kill off the lakes'
plants and lower water quality.21

The use of intense
lights for fishing at night attracts large numbers of fish. This method leads
to over-fishing and contributes to the decline of fish worldwide. Artificial
lights at night have caused behavioral and physiological changes in salamanders
as well.

In summary, whether
outdoor light is directly next to a species habitat or located at some distance,
as through sky glow, the combined effects of artificial lighting on vast numbers
of nocturnal species have the potential to disrupt the functioning of entire
ecosystems by disrupting balances in competition and the predator-prey relation,
among others.

The dark-skies
education efforts described below aim to heighten awareness of light pollution
as a global problem with a local solution. Education efforts have proven to
be most effective when people get physically involved. For example, "star
hunts" or "star counts" provide people with a fun, fast and no-frills
way to acquire heightened awareness about light pollution through firsthand
observations of the night sky. Over the past two years the GLOBE at Night program
(led by National Optical Astronomy Observatory (NOAO) and the GLOBE Program
educational outreach staff) has enabled thousands of citizen-scientists around
the world to contribute measurements of their local sky brightness to a growing
global database in two ways: simple unaided-eye observations that anyone can
do and quantitative digital measurements through a handheld, well-calibrated
sky-brightness meter. Indeed, GLOBE at Night represents a landmark in the emerging
informal science education thrust of citizen-science projects. See http://www.globe.gov/globeatnight/
on how you can participate.

With a couple mini
light flashlights and a PVC cap, you can illustrate the effects of lighting
on our view of the night sky and how simple shielding fixtures can reduce light
pollution while at the same time making the lighting more effective. This simple
and effective demonstration is outlined on the Paper Plate Education website:
http://analyzer.depaul.edu/paperplate/lights.htm.

18.
Kenneth D. Frank (1988). "Impact of outdoor lighting on moths". Journal
of the Lepidopterists' Society 42: 63-93. (Reproduced on-line in part by
the International Dark-Sky Association on Information Sheet #109.)